A slide of an Auliscus sp. from Oamaru, New Zealand. Label also has ‘fraglich as’ written in pencil. Single example, mounted with the rim upwards towards the coverslip (an underside view). Prepared by William Allott Firth. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 33 images stacked in Zerene (Pmax).
As for what this, I am not 100% sure.
Maybe Auliscus elegans var. subpunctata. Auliscus elegans var. subpuncatatus Rattray, 1999. Published in: Rattray, J. (1888). A revision of the genus Auliscus Ehrenberg and of some allied genera. Journal of the Royal Microscopical Society 1888: 861-920, 5 pls [XII-XVI]. Page 873, Plate XVI [16], Figure 2.
Maybe Pseudauliscus pulvinatus (Cleve) Rattray, 1886. Published in: Rattray, J. (1888). A revision of the genus Auliscus Ehrenberg and of some allied genera. Journal of the Royal Microscopical Society 1888: 861-920, 5 pls [XII-XVI]. Page 906. This name is currently regarded as a synonym of Auliscus pulvinatus Cleve, 1885. Published in: Cleve, P.T. (1885). On some fossil marine diatoms found in the Moravian “Tegel” from Augarten, near Brünn. Journal of the Quekett Microscopical Club, Series 2 2(13): 165–177, plates 12–13. Page 171, Plate XII, Figure 9.
Currently leaning towards P. pulvinatus based on D&S Oamaru Diatoms book descriptions and images. But not completely convinced.